Old buildings accumulate a lot of surface dirt over many years. General staining is caused by a gradual build up of carbon deposits in the air. Other stains can be caused by random paint splashes, cement stains or dripping pipes and damp walls which cause a build up of moss etc on the brick surface.
Green algae and moss is usually easily removed by jet washing alone but paint, cement or carbon staining needs to be treated with the appropriate chemical to soften or break down the offending stain, prior to jet washing.
A B Kirby & Sons are experienced in these procedures and the use of the appropriate chemicals needed. The correct chemicals are usually applied with a low pressure sprayer or brushed on then, after the necessary dwell time, are hosed off with a commercial, petrol powered jet-washer. This action may need to be repeated several times to remove all of the staining, leaving the brickwork clean and ready to be repointed.